Method and apparatus for inside blowout preventer drilling tool

ABSTRACT

A method and apparatus for a normally open inside blowout preventer drilling tool adapted for mounting in a drilling string for controlling undesired flow of well fluids in the drill string and for enabling the sensing and determination of well conditions below the tool effecting undesired flow in the drill string.

United States Patent Mott 1 1 Jan. 21, 1975 METHOD AND APPARATUS FORINSIDE 3,078,923 2/1963 Tausch 166/224 S LO O PREVENTER DRILLING TOOL3,126,908 3/1964 Dickens 166/224 S 3,200,837 8/1965 Brown 175/318Inventor: Ja Mott, Houston, 3,667,505 6/1972 Radig 137/629 [731 AssigmCompany, Houston 3:292:33?) 3113 13 5122???? 11:1: 122/313 [22] Filed:Sept. 21, 1973 3,696,868 10/1972 Taylor, .Ir,... 166/224 5 3,741,2496/1973 Lcutwyler.... 166/224 5 1 1 PP 5 3,783,942 1/1974 M011 175/311152 11.5. c1 166/315, 137/461, 137/498, Prlmary LePPlnk 166/224 A, 251/5751 1111. C1 E2lb 43/01, E21b 43/12 1571 ABSTRACT [58] Field of Search166/224, 224 S, 250, 314, A method and apparatus for a normally openinside 166/315; 137/630, 629, 495, 496, 505, 460, blowout preventerdrilling tool adapted for mounting 461, 498; 175/317, 318; 651/57 in adrilling string for controlling undesired flow of well fluids in thedrill string and for enabling the sens- [56] References Cited ing anddetermination of well conditions below the UNITED STATES PATENTS tooleffecting undesired flow in the drill string. 2,921,601 l/l960 Fisher,Jr 166/224 S 45 Claims, 5 Drawing Figures METHOD AND APPARATUS FORINSIDE BLOWOUT PREVENTER DRILLING TOOL CROSS-REFERENCES TO RELATEDAPPLICATIONS The method and apparatus set forth in the presentapplication is related to the disclosure of my application now entitledInside Blowout Preventer Drilling Tool," filed Nov. 24, 1971 andassigned Ser. No. 201,878, now US. Pat. No. 3,783,942, and myapplication Ser. No. 212,260, filed Dec. 27, 1971, and entitled DrillingTool.

BACKGROUND OF THE INVENTION This invention relates to the field of amethod and apparatus for a drilling tool for controlling blowout flowthrough the bore of a tubing.

Prior Art inside blowout preventer drilling tools, such as disclosed inmy applications identified hereinabove, have been of the type having avalve element which was operated to normally be urged to move to andremain in the closed position and which was operably moved to the openposition by a valve operator means in response to certain conditions oroperations, insuring flow in the desired downwardly direction. When suchprior art valves operated to shut-in a blowout flow, it was necessary tocirculate a heavier drilling fluid in the well to bring the wellpressure back under control. In addition, the prior art valves requireda greater pressure, on the order of several hundred PS1. in the bore toopen and hold the valve in the open position. Of course with the valveclosed, the well pressure below the tool effecting the blowout could notbe sensed for determining the weight or hydrostatic pressure of drillingfluid required for controlling the well and the driller was forced toeither guess or estimate what increase in density of the drilling fluidwas required to bring the well under control. The expense of both thelost drilling time while circulating to bring the well under control andof the weight additives for increasing the density of the drilling fluidhad limited the use and acceptance of prior art tools.

SUMMARY OF THE INVENTION This invention relates to the field of a newand improved method and apparatus for an inside blowout preventerdrilling tool.

In the present invention, an inside blowout preventer drilling tool isarranged to operate in response to substantially equal drillingpressures for enabling drilling operations and for closing the flowpassage of a drilling string when well conditions effect uncontrolledflow. With the present invention, well conditions below the drillingtool may be sensed or measured for determining the requirements forbringing the well back under control.

An object of the present invention is to provide new and improved insideblowout preventer drilling tool apparatus.

A further object ofthe present invention is to provide a new andimproved method for operating an inside blowout preventer drilling tool.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial side view, insection, of the apparatus of the present invention in the open position;

FIG. 2 is a partial side view, in section, with the apparatus of thepresent invention operated closed;

FIG. 3 is a partial side view, in section, of another form of theapparatus of the present invention operated open;

FIG. 4 is a partial side view, in section, with the apparatus of FIG. 3operated closed; and

FIG. 5 is a side view, in section, of a well with the apparatus of thepresent invention operably installed in the drill string.

DESCRIPTION OF THE PREFERRED EMBODIMENT As illustrated in FIG. 5, theinside blowout preventer drilling tool of the present invention,generally designated T in the FIGS, is adapted for mounting in a wellconduit or drill string S above the drill bit B to control undesiredupwardly or uncontrolled blowout flow which may occur during drillingoperations when a high pressure formation F is penetrated by the drillbit 8. A rotary table means R at the surface or ground level G co-actswith a kelly K for imparting rotational movement to the drill string Sand the drill bit B for providing the desired rotary cutting actionwhile a hoisting means (not illustrated) controls the vertical,longitudinal movement of the drill string S and the drill bit B in thewell known manner. During drilling operations, drilling fluid iscirculated by a pump means P on the surface G through a swivel or othersuitable connection C into the bore of the kelly K and the bore passageX of the drill string 5 to the drill bit B where it is jetted into theborehole H through the nozzles N. The drilling fluid then circulatesback to the surface or ground level G in the annular area between thedrill string S and the walls of the borehole H to the pump supply pit ortank W where it is available for recirculation by the pump means P.Normally, the weight of the column of drilling fluid in the bore hold Hprovides a sufficient hydrostatic pressure to control the fluid pressurefound in the formation F. When the fluid pressure in the formation Fexceeds the hydrostatic head or well conditions are out of control forany reason, the inside blowout preventer drilling tool T of the presentinvention operates to control the flow in the bore X.

In the embodiment of the drilling tool T illustrated in FIGS. 3 and 4,the tool T includes a tubular member frame 10 mounted with and forming aportion of the drill string S at a desired location in the string S.Threads 11 and 12 formed on the frame 10 provide the means forconnecting the upper and lower ends, respectively, of the frame 10 inthe drill string S. A full opening flow passageway 13 is providedthrough the frame 10 to enable circulation of drilling fluid to thedrill bit. Formed through the frame 10 is one or more radially extendingports 14 for communicating the well pressure in the bore hole H adjacentexterior surface 15 of the frame 10 to the flow passage 13.

The drilling tool T further includes a closing means, generallydesignated 20, movable to and from an open position for enabling desiredflow through the drill string S and a closed position for blockingundesired upwardly flow through the drill string S and an operatormeans, generally designated 30, for effecting desired operationalmovement of the closure means 20.

The closure means 20 includes a substantially spherical or ball shapedmember 21 having a full bore opening or passageway 22 extendingtherethrough and seal means or seats 23 and 24, located above and belowthe ball 21, respectively, engaging a spherical surface 25 for effectinga fluid tight seal with the ball 21 to block leakage of fluidtherebetween. The ball 21 rotates between the open position in which theopening 22 is substantially aligned with the bore flow passage 13 and aclosed position in which the opening 22 is located substantiallytransverse to the bore 13 for blocking flow with the ball 21. The fullbore opening 22 provides a cross-sectional flow area therethroughsubstantially equal to the cross-sectional flow area of the bore X ofthe drill string S to reduce or minimize pressure loss duringcirculation of the drilling fluid.

The operator means 30 includes a movable operator sleeve member 31located adjacent and operably connected with the ball 21 to effect thedesired pivoting or rotational movement thereof. The ball 21 includesspaced parallel circular flat surfaces 26 having radially extendingrecesses or grooves 27 formed therein. Pins Y threadedly secured to thesleeve 31 at aligned eccentrically located positions extend within thegrooves 27 to effect rotation of the ball 21 when there is relativelongitudinal movement between the ball 21 and the operator sleeve 31. Inthe present embodiment, the ball 21 only rotates when the sleeve 31moves longitudinally to and from a first or down position (FIG. 3) forrotating the ball to the opening position and a second or upper position(FIG. 4) for rotating the ball to the closed position. If furtherexplanation or description of the manner of rotating the ball 21 isdesired, reference may be had to my co-pending applications identifiedhereinabove, or to U.S. Pat. Nos. 3,126,908; 2,894,715; 3,667,505; Re.25,471 and 3,035,808.

The operator means 30 includes a piston means 32 formed by the sleeve 31for effecting movement of the sleeve 31 to move ball 21 in response tothe various pressure urgings on the piston means 32. The sleeve 31 isslidably sealed to the housing by O-rings 34a and 34b carried by thesleeve 31 resulting in an upper annular shoulder 33 of the sleeve 31forming a first or upwardly facing annular surface for urging movementof the sleeve 31 to the lower position in response to the pressure in afirst expansible chamber 35 formed by the sleeve 31 in the housing 10urging on the shoulder 33. The annular expansible chamber 35communicates with the flow passage 13 through a plurality of ports 36formed in the housing 10 for exposing the shoulder 33 to the fluidpressure present in the flow passage 13 and the bore X of the drillstring S.

The sleeve 31 is slidably sealed to the housing 10 by O-rings 37 and 38for forming a second or lower expansible chamber 39 with a lower annularshoulder 40 of the sleeve 31 forming a second or downwardly facingannular surface for urging movement of the sleeve 31 to the upperposition in response to the fluid pressure in the chamber 39 urging onthe shoulder 40. The lower annular expansible chamber 39 communicatesthrough the ports 14 with the area adjacent the exterior of the tool T.An O-ring 41 mounted with a lower removable sleeve 42 of the housing 10blocks leakage of fluid between the expansible chamber 39 and the flowpassage 13 of the housing 10.

The removable sleeve 42 includes a smaller outer diameter upper portion43 above the O-ring 38 forming an upwardly facing annular shoulder 44which engages a downwardly facing annular shoulder 31a (FIG. 3) on thesleeve 31 for providing a lower movement stop for the sleeve 31. Thedifferent outside diameter portions of the sleeve 42 cooperate with themovable sleeve 31 to form an annular expansible chamber 45 above theshoulder 44, which communicates with the flow passage 14 through aplurality of circumferentially spaced ports 46 formed through the upperportion 43 of the sleeve 42 for urging on the pressure responsive effective surface of the sleeve 31 formed by the shoulder 31a to urge upwardmovement of the sleeve 31 to the upper position in response to thepressure in the flow passage 13 in the bore X of the drill string S.

The operator means 30 further includes a spring 47 or means for urgingthe operation or movement of the sleeve 31 to the lower position whichis located in the upper expansible chamber 35. The spring 47 is mountedwith the housing 10 by engagement with the shoulder 48 formed by anupper removable sleeve 49 forming a portion of the housing 10 andengages the shoulder 33 of the sleeve 31 for urging movement of thesleeve 31 to the lower position.

Of the four forces urging operating movement of the sleeve 31, two areurging downward movement and two are urging upward movement. The spring37 and the pressure in the chamber 35 urge downwardly to open the ball21 while pressure in the chambers 39 and 45 urge to close the ball 21.However, fluid pressure communicated into the chambers 45 and 35 is thesame when the ball 21 is rotated open and therefore these urgings wouldbe offsetting or mutually cancelling to a predetermined extent. Thepressure in the chamber 35 urging on the greater pressure responsivearea 33 would still provide a net downwardly urging on the sleeve 31predetermined by the difference in the relative size of the pressureresponsive effective surface areas 33, 31a and 40. In the embodimentillustrated in FIGS. 4 and 5; the pressure responsive area 33 is equalto the pressure responsive areas of the shoulders 14 and 31a. By varyingthe relative size of the effective areas 14 and 310, the operatingparameters of the valve may be predetermined varied or controlled.

For example, when the ball 21 is rotated open the pressure in the wellconduit urging a portion of the surface 33 not offset by the surface 31atogether with the spring 37 will urge the sleeve 31 to remain in thelower position. To move the sleeve 31 to close the ball 21 the pressureexteriorly of the tool T and in the chamber 42 must provide an urging onthe shoulder 40 of the sleeve 31 exceeding the combined urging of thepressure in the drill string urging downwardly on the non-offset portionof the surface 33 and the urging of the spring 47. Of course, theshoulder 40 may be provided with a predetermined larger effectivesurface area than that of shoulder 33 in order that the valve will closewhen the pressures are substantially equal. With the ball 21 rotatedclosed (FIG. 4) the pressure exteriorly of the tool effecting closure ofthe ball 21 will also be communicated through the drill bit nozzles Ninto the flow passage 13 below the ball 21 and into the chamber 45. Thewell pressure effecting closure will then be present in both expansiblechambers 39 and 45 for maintaining the sleeve 31 in the upper positionand the ball 21 rotated closed. To move the sleeve 31 downwardly to openthe ball 21, the pressure in the bore X of the drill string S above theball 21 is increased by the use of pump means P or the like to approachthe pressure in the chambers 45 and 39 urging the ball closed. When theincreased pressure in the flow passage 13 above the ball 21 approachesthe pressure in the chambers 39 and 45 to bring the fluid pressureurging on the sleeve 31 within a predetermined offsetting range, thespring 37 will move the sleeve 31 to the lower position and open theball 21. Of course, selecting a spring 37 with a desired spring constantwill control or predetermine the range or value to which the pressure inthe chamber must approach the pressure in the chambers and 39 to openthe valve. With this arrangement, the valve is preferably set to operateclosed in response to the urging of a pressure differential rangeapproaching PSI on the sleeve 31.

When the ball 21 is rotated open, the pressure in the flow passage 13above the ball 21 will be increased by equalization in which increasedpressure will be communicated into the chamber 35 for equalizing oroffsetting the pressure urgings on the sleeve 31, which assures that thesleeve 31 will move to the lower position and eliminates the possibilityof potentially damaging flow throttling by the ball 21.

In summary, increased pressure from exteriorly of the tool T, in thechamber 39, will effect closing rotation of the ball 21 while increasingthe pressure in the bore X of the drill string S above the ball 21 toapproach within a selected or predetermined range of the pressureexteriorly of the tool T will rotate the ball 21 open.

A second embodiment of the well tool T of the present invention having atubular assembly 100 dimensioned to be introduced or inserted in theflow passage 101 of a drill string pipe or sub 102 for controlling flowof fluid to the drill string S is illustrated in FIGS. 1 & 2. The sub102 is provided at its upper end with threads 103 and at its lower endwith threads 104 for connecting the sub 102 in the drill string S forforming a portion thereof at a desired location. The flow passage 101 isformed adjacent the threads 103 to provide a downwardly facing annularshoulder surface 104 which engages the tubular assembly 100 for blockingupward movement of the tubular assembly 100 from the flow passage 101 ofthe sub 102. The portion of the drill string S below the sub 102 securedto the thread 104 blocks downward movement of the tubular assembly 100from the flow passage 101 of the sub 102.

The tubular assembly 100 includes a longitudinally extending passagewayor opening 106 extending therethrough for enabling communication withthe bore X of the drill string S through the opening 106. The open ing106 is provided with a cross-sectional flow area substantially equal tothe cross-sectional flow area of the bore X of the drill string S forforming a full bore opening tool T. The tubular assembly 100 carries alower seal ring means 107 for effecting a seal between the tubularassembly 100 and the sub 102 for blocking the passage of fluidtherebetween and directing the flow of the fluid in the bore X of thedrill string S through the bore 106 of the tubular assembly 110. Theseal means 107 is also arranged for enabling fluid pressure introducedbetween the sub 102 and the tubular assembly 100 to force or urge thetubular assembly 100 to move downwardly from within the sub 102 when theengagement at thread 104 is disconnected.

The tubular assembly 100 includes an upper fixed sleeve 108 having anupper annular shoulder 1080 which partially engages the shoulder 104 ofthe sub 102 for holding the tubular assembly 100 against upward movementin the sub 102. Concentrically positioned within the longitudinallyextending opening through the sleeve 108 and secured therein is thesleeve 109 having an upwardly facing shoulder 109a engaging a downwardlyfacing shoulder l08b for blocking upwardly movement of the sleeve 109relative to the sleeve 108. A restraining device or snap ring 110partially fits in an annular groove 1091; in the sleeve 109 and engagesthe shoulder 108a to block downward movement of the sleeve 109 relativeto the sleeve 108. The sleeve 108 carries a seal ring 111 for effectingan annular seal with the sub 102 to block leakage or passage of fluidbetween the sub 102 and the tubular assembly 100.

The sleeve 108 extends downwardly from the seal 111 to mount an annularseal ring 112 at the lower end of the sleeve 108. The inside surface108C forming the opening through the sleeve 108 includes a downwardlyfacing annular shoulder 108d engaging or resting on a plurality ofcircumferentially spaced radially outwardly extending lugs orprojections 113a formed on a sleeve 113 for blocking upward movement ofthe sleeve 113 relative to the sleeve 108. The sleeve 113 forms aportion of the full bore opening for flow passage 106 through thetubular assembly and concentrically mounts at its lower end a seat ring123 engaging a bore closure means or ball 12] for blocking flow throughthe opening 106. Concentrically mounted at the upper end of the sleeve113 by threads 113b is a resilient tubular diaphragm 150 which issecured at its upper end to threads 109s of the sleeve 109 to form aportion of the flow passage 106 through the tool T. The diaphragm 150 isradially flexible for purposes to be set forth in greater detailhereinafter.

Located below the ball 121, the illustrated tubular assembly 100includes the sleeve 114 concentrically mounting a lower seat ring 124 insealing engagement with the ball 121 and forming a portion of theopening 106 through the tubular assembly 100. A securing ring 115 issecured to the lower outer threaded surface 114a of the sleeve 114 forproviding a lower limit stop to a relatively movable sleeve 116 byengagement of a downwardly facing annular shoulder 116a with an upwardlyfacing annular shoulder 115a of the securing ring 115. Concentricallymounted exteriorly of the sleeve 114 above the securing ring 115 is aseal carrying ring 117 for mounting the seal ring 107 and which alsomounts an O-ring 118 for blocking lockage of fluid between the sealmounting ring 117 and the sleeve 114. The seal carrying ring 117 formsan upwardly facing annular shoulder 117a which engages a downwardlyfacing annular shoulder 11% formed on an outer surface 1140 of thesleeve 114 to block or limit upward movement of the seal carrying ring117 relative to the sleeve 114. Positioned between an upwardly facingannular surface 116b and a downwardly facing shoulder 11712 of the ring117 is a biasing or spring means 119 to provide a length adjustor orcompensator for the tubular assembly 100 for holding the tubularassembly 100 in engagement with the shoulder of the sub 102 whileenabling fluid tight engagement of threads 104 with the drill string S.The sleeve 116 engages the drill string S with the lower annularshoulder 1160 to block downward movement of the tubular assembly 100from the flow passageway 101 of the sub 102 and the limited range oflongitudinal movement of the sleeve 116 assures the tubular assembly 100is held in engagement with the annular shoulder 105 despite variationsin makeup of the drill string S at threads 104.

The embodiment of the tool T, illustrated in FlGS. 1 and 2, alsoincludes a bore closure means 120 and an operator means 130 foreffecting operation of the bore closure means 120.

The bore closure means 120 includes the ball 121 and the seats 123 and124 which engage an outer spherical surface 121a for effecting annularfluid type seals with the ball 121. The ball includes a flow passage121b, formed therethrough which preferably is of the samecross-sectional flow area as that of the opening 106 to the tubularassembly 100 in order that the well tool T provides a full bore openingtherethrough substantially equal to the cross-sectional flow area of thebore X of the drill string S to minimize pressure loss of the drillingfluid flowing through the tubular assembly 100. The ball 121 isrotatably mounted with the tubular assembly 100 to align the opening12111 with the passage 106 for enabling flow through the opening 106 andwhich is rotatable to a closed position with the opening 121bsubstantially transverse to the opening 106 for blocking flow of fluidthrough the opening 106 and the bore X of the drill string S.

The operator means 130 includes a longitudinally movable sleeve operatormember 131 concentrically mounted exteriorly of the ball 121 and whichis movable to and from a first or lower position effecting openingrotation of the ball 21 (FIG. 1) and a second or upper positionaffecting closing rotation of the ball 121 (FIG. 2). The operator sleeve131 carries inwardly projecting lugs or pivot pins 132 which areeccentrically secured to the sleeve 132 for longitudinal movement andwhich extend within radial recesses 121c formed in the flats 121d foreffecting the desired rotation of the ball 121.

The operator means 130 includes a piston means 133 preferably formed byan upper operator piston sleeve 134 and a lower piston operator sleeve135 secured together by threaded engagement at 136. An upwardly facingannular shoulder 135a of the lower sleeve 135 engages the bottom of theoperator sleeve 131 while a downwardly facing annular shoulder 134aengages the top of the operator sleeve 131 for securing the threeoperator sleeves to form an integral operator unit or member movinglongitudinally for rotating the ball 121 in the desired manner.

The lower piston sleeve 135 carries the seal 137 for effecting a slidingseal with the sub 102 for blocking leakage offluid therebetween. Mountedon the exterior surface 114d of the sleeve 1 14 is a seal 138 foreffecting a sliding seal between the sleeve 135 and the sleeve 114. Theannular area of the sleeve 135 between the seals 137 and 138 form adownwardly facing pressure responsive surface which will be referred toand identitied hereinafter as the lower annular shoulder 135b.

The tubular assembly 100, the operator sleeve 135 and the sub 102 form asecond annular expansible chamber 140 defined by seal rings 137 and 138at the upper end and seal rings 107 and O-ring 118 at the lower end.Fluid pressure in the chamber 140 urges on the annular pressureresponsive effective surface area 135b of the sleeve 135 to urge theoperator sleeves 132, 133 and 135 to the upper or second position forrotating the ball 121 closed. Fluid pressure in the chamber 140 alsourges on the upwardly facing annular shoulder 117a of the seal ring 117for urging movement of the tubular assembly 100 from the flow passage101 of the sub 102 when the drill string is disconnected at thread 104.Extending through the sub 102 is one or more flow ports 102a forcommunicating the chamber 140 with the area adjacent an exterior surface102b of the sub 102. The flow port or opening 102a may be provided withthreads 102b for connection with a supply of fluid pressure to force thetubular assembly 100 from the flow passage 101 when the drill string Swas disconnected at threads 104. To accomplish this removal it isnecessary that the pressure responsive effective surface area 1170 belarger than the pressure responsive effective surface area between theseals 137 and 138 to provide a net downwardly urging on the tubularassembly 100.

As best illustrated in FIG. 1, the movable upper operator sleeve 134carries seal rings 141 and 142 to effect sliding annular seals with thesub 102 and the sleeve 113 of the tubular assembly 100, respectively, toblock leakage of fluid by the sleeve 134. The sleeves 141 and 142, alongwith the diaphragm 150, define a first or upper enclosed annular chamber143 in communication through the openings between the lugs 113a. Fluidpressure in the chamber 143 will urge on the upwardly facing pressureresponsive annular shoulder surface 134b of the sleeve 134 for movingthe operator sleeves 132, 134 and 135 to the first or lower position forrotating the ball 121 to the open position.

The chamber 143 is filled with a pressure transmitting fluid, such ashydraulic oil or grease, in order that fluid pressure in the bore of thedrill string S and the flow passage 106 above the ball 121 urging on aninner surface 150a of the diaphragm will be transmitted to the pressureresponsive surface 134b for urging thereon. The pressure in the flowpassage 106 will move or urge the diaphragm 150 to flex radiallyoutwardly as the operator sleeve 134 moves downwardly to continuallytransmit the pressure in the flow passage 106 with an outer surface15011 of the diaphragm urging on the pressure transmitting fluid. Withthis arrangement solid particles in the drilling fluid are excluded fromthe pressure responsive chamber 143 and will not interfere with, bind,hinder, or block movement of the operator sleeves 132, 134 and 135.

The upwardly facing pressure responsive surface l34b is also formed toeffect secondary seals with an inner annular seal 144 carried by thesleeve 113 and the outer annular seal 112 carried by the sleeve 108 whenthe sleeve 134 is in the upper position. The secondary seal so effectedby seal rings 144 and 112 reduce the effective pressure responsivesurface area l34b of the sleeve 134 when the ball 121 is in the closedposition. As the sleeve 134 commences to move downwardly for rotatingthe ball 121 open and away from the seats 112 and 144, the size of thepressure responsive surface area 134b is increased for assuring positivemovement of the sleeve 134 to the lower position. This arrangement avoidequalizing of the pressure urging on the operator 132 between the upperand lower positions resulting in the ball 121 rotated only partiallyopen. When the ball 121 is partially open, the pressure drop across theflow passage 106 is increased and damage to the sealing surfaces isprobable.

The ratios of the pressure responsive efiective surface area of thesurface 134b when sealed by the 0- rings 112 and 144 and when spacedfrom those secondary seals to the pressure responsive effective surfacearea 135b will predetermine or control the pressure value ordifferential between the chambers 143 and 140 for effecting operation ofthe ball 121. With this illustrated embodiment, a pressure in thechamber 140 approximately 25 psi higher than the pressure in the chamber143 will effect closing rotation of the ball 121 from the open position.The The secondary sealing arrangement preferably requires an increasedpressure exceeding the well pressure to open the ball 121. Both welltool embodiments disclosed herein are arranged to be unusually sensitiveto the pressure differential urgings thereon and are operable inresponse to substantially equal or slightly different pressures whencompared to the prior art inside blowout preventer well tools.

The operator means 130 includes releasable latching or locking means forsufficiently delaying movement of the operator sleeve from the lowerposition to prevent or block momentary pressure fluctuations foreffecting closing rotation of the ball 121. Extending downwardly fromthe shoulder 135b of the lower operator sleeve 135 is a plurality ofresiliently deformable circumferentially spaced arms or projectionshaving radially inwardly extending lugs 161 formed on the lower end. Thelugs 16l are aligned with an annular recess 114a formed in the outersurface 1140 of the sleeve 114 for providing a downwardly facing lockingshoulder 1l4f for engaging an upwardly facing surface 1610 of the lugs161 for holding the ball 121 in the open position. The arms 160 willflex radially outwardly to enable the lugs 161 to be wedged from beneaththe surface ll4f by a greater pressure in the chamber 140 and in thechamber 143 for a small, but effective, length of time to flex thefingers 160 outwardly. The deformation of the fingers 160 is controlledby an adjustment ring 162 concentrically mounted exteriorly of thefingers 160 by moving the ring 162 longitudinally towards the lugs 161.The delay in closing may be increased by increasing the amount of forcerequired to disengage the lugs 161 from the recess 114a. The adjustmentring 162 is provided with a set screw 163 to hold the adjustment ring162 in the desired position along the arms 160. Preferably theadjustment ring 162 is set to insure that the ball 120 is not rotatedclosed as the drill string is lowered in the bore hold H towards theformation F. This enables the bore X of the drill string S to fill withdrilling fluid in the bore hole H through the nozzles N of the drill bitB and avoid the need to connect the drill string S with the pump means Pfor filling the drill string S above the tool T with drilling fluid toprevent collapse of the drilling string S. This feature is accomplishedin the first described embodiment by proper selection of the spring 47for maintaining the ball 21 rotated open.

OPERATION AND USE OF THE PRESENT INVENTION In the operation and use ofthe first described embodiment (FIGS. 3 & 4) of the well tool T of thepresent invention, the tubular frame is connected in the drill string 5in the desired location. Pressure is then increased in the bore X of thedrill string S above the ball 22 for urging on the surface 33 to effectopening rotation of the ball 22. "Thereafter, as additional sections ofdrilling string are added and the well tool T lowered deeper in the borehole H, the urging of the spring 47 will maintain the ball 21 in theopen position for enabling filling of the bore X of the drill string Sthrough the nozzles in the drill bit B.

When drilling operations are commenced, the drilling fluid pressure inthe bore X of the drill string S will exceed the pressure in the annulusbetween the drill string and the walls of the bore hole H and the ball31 will remain in the open position. When unexpected high pressureformations are encountered the formation pressure will be sensed by theoperator sleeve 131 by communication through the flow port 14 into theexpansible chamber 39 for urging the operator sleeve to the upperposition and closing the bore X of the drill string S with the ball 21.The operator sleeve 22 continually compares the pressure urgings in thechamber 39 and the chamber 35 for closing the ball 21 when the pressurein the annulus exceeds the pressure in the bore X of the drill string Sabove the ball 21 by the predetermined value.

When it is desired to rotate open the ball 21, pressure in the flowpassage 13 above the ball 21 is increased until it approaches within thepredetermined value of the well pressure present in the expansiblechambers 39 and 45 as the well pressure is communicated through thenozzles into the drill bit B into the flow passage 13 of the well tool Tbelow the ball 21. When the pressure above the ball 21 is increasedsufficiently, the operator sleeve will sense the increased pressure andcompare it with the well pressure to enable the spring 47 to move theoperator sleeve 31 down for rotating the ball 21 back to the openposition. At this time the greater pressure in the bore 13 will be belowthe ball and will equalize with the pressure above the ball 21 bycommunication through the opening 22 as the ball 21 rotates open. Thisequalization will result in a pressure increase in the bore of the wellconduit above the ball for holding the ball 21 in the open position andwhich may also be sensed or measured ground level G. The nozzles N ofthe drill bit B serve to throttle flow into the bore X of the drillstring for providing a sufficient pressure differential between the boreX of the drill string S and the well annulus to close the ball 21whenever pressure decreases in the bore X of the drill string S. As longas the pressure in the bore X in the drill string S is maintained withinthe predetermined range for holding the valve open, the ball 21 willremain in the open position and the flow, choked by the nozzles N, intothe bore X of the drill string S may be bled off at the ground level Gthrough the valve designated at 160. Thus, an inside blowout preventerdrilling tool is provided which enables a small pressure differentialflow rate upwardly through the bore of the drill string under controlledconditions, but which will shut in the drill string when the upwardlyflow rate pressure differential exceeds the predetermined value orcontrol is lost.

In the use and operation of the second embodiment of the presentinvention, the tubular assembly is assembled in a manner readilyapparent from the drawings and mounted with the drill string S byinsertion into the flow passage 101 of the sub 102. When the sub 102 isconnected in the drill strings with threads 104 and the string S engagessleeve 116, the tubular assembly 100 is moved to engage the annularshoulder 105 of the sub 102 for securing therein. Pressure in the bore Xof the drill string S above the ball 121 is then increased for urging onthe diaphragm to flex to increase the pressure in the upper expansiblechamber 143 to rotate the ball 121 open. With the ball 121 rotated open(FIG. 1), the operator sleeve 131 is in the lower position and the lugs161 engage the tapered shoulder l14f for latching the operator unit inthe lower position. As additional drill string S is added above the welltool T and the tool T lowered into the bore hole H, the lugs 161 andresilient fingers 160 are sufficient to hold the ball 121 in the openposition to enable equalization of the levels of drilling fluid in thebore X of the drill string S and in the borehole H to delay closingrotation of the ball 121 and enable filling of the bore X of the drillstring S through the nozzles N of the bit B.

During normal drilling operations, pressure of the drilling fluid in thebore X is greater than the pressure exteriorly of the well tool T andthe ball 121 is held in the open position. When the pressure in theborehole H exteriorly of the tool T exceeds the pressure in the bore Xof the drill string S, the greater pressure will be sensed by thesurface l35b and compared with the pressure urging on the surface 134bfor urging the operator unit to move upwardly for closing the ball 121.The greater pressure in the chamber 140 required for effecting closureof the ball 121 may be predetermined or controlled by the ratio of theeffective surface area l35b to that of the surface l34b. In addition,the adjustment ring 162 will influence or assist in predetermining thepressure differential needed for closing the valve.

With the valve in the closed position, the pressure in the bore X of thedrill string S below the ball 121 will equalize with the pressure in thebore hole H effecting closure by communication below the ball 121 willbe communicated along threaded engagement 136 for effectively urgingupwardly on the operator unit between the seals 141 and 142 and thus theopening and closing pressure responsive surface effecting seals will beidentical. However, the opening pressure responsive surface 13412 isalso sealed by the secondary seals 112 and 144 which in effect reducethe effective surface area of the pressure responsive surface 134b. As aresult, the pressure in the bore X above the ball 121 must be increasedto a value greater than or vary from the pressure in the bore X belowthe closed ball 12] to effect opening rotation thereof. Once the ball121 is rotated open and the pressure equalized in the bore X of thedrill string S, the well pressure may be bled off through the valveindicated at 160. The pressure must be bled off at a rate approximatingthe flow into the bore X of the drill string S through the nozzles N toprevent a sufficient pressure differential to rotate the ball 121closed. After bleeding the pressure for a sufficient amount of time, thevalve 160 may be shut in with the ball 121 remaining in the openposition.

As both embodiments of the present invention may be held in the openposition by controlling the pressure in the bore X of the drill string Sto be substantially equal to the well pressure, well conditions existingbelow the tool T may be determined. The detail sequence for opening thetool T of each embodiment has previously been set forth herein. Inessence, this procedure entails increasing the pressure in the bore X ofthe drill string S above the tool T to a sufficient value for effectingopening of the tool T and thereafter manipulating the valve indicated160 to maintain the tool T in the open position. With either of thetools operated open and pressure equalized in the bore X, various wellconditions may be determined. Samples of the drilling fluid from thedrill bit B location may be determined by bleeding a sufficient quantityof drilling fluid from the drill string S. Also, with the valveindicated at shut in, the static well pressure may be read or measuredby a pressure guage device, indicated at 161. The measured wellpressure, when compensated by the hydrostatic pressure of the column ofdrilling fluid in the bore X, will enable the operator to determine thewell pressure at the level of the formation F or the tool T.

With the well pressure at the formation known to the driller, therequired or necessary density of the drilling fluid to provide asufficient hydrostatic pressure head at the formation F to bring thewell under control may be easily calculated or determined. This avoidsthe expense of using too heavy a drilling fluid or wasted circulationtime in bringing the well under control. The desired density of drillingfluid may then be made up in the reservoir W and circulated down thebore X of the drill string S through the drill bit B and back to thesurface exteriorly of the drill string S to bring the well back undercontrol and enable resumption of drilling opera tions.

The foregoing disclosure and description of the invention areillustrative and explanatory thereof, and various changes in the size,shape, and materials as well as in the details of the illustratedconstruction may be made without departing from the spirit of theinvention.

I claim:

1. A method of operating a well tool for controlling undesired flow in awell conduit, including the steps of:

mounting the well tool with the well conduit to control flow through thewell conduit;

sensing the fluid pressure exteriorly of the well conduit adjacent thewell tool;

comparing the sensed pressure exteriorly of the well conduit with thefluid pressure in the well conduit; and

opening the well tool to enable flow in either direction through thewell conduit when the pressure in the well conduit approaches within apredetermined amount of the sensed pressure exteriorly of the wellconduit wherein the well tool is opened to enable the flow when thepressure in the well conduit is less than the pressure exteriorly of thewell tool by the predetermined amount.

2. The method as set forth in claim 1, including the step of:

closing the well tool to block flow through the well conduit when thesensed pressure exceeds the pressure in the well conduit by thepredetermined amount of pressure.

3. The method as set forth in claim 1, including the step of:

latching the well tool open to delay operation sufficiently to preventmomentary pressure fluctuations from operating the well tool.

4. The method as set forth in claim 3, including the step of:

releasing the latch when the sensed pressure exceeds the pressure in thewell conduit by the predetermined amount of pressure for closing thewell tool.

5. The method as set forth in claim I, wherein the step of mountingincludes the step of:

locating the well tool in the flow passage of the well conduit to enabledesired changing of the well tool by disconnecting the well conduit atone location.

a. controlling the pressure in the well conduit to open the well tool;and

b. determining the value of the sensed pressure through the open welltool.

8. A method of determining well conditions at a location adjacent aported drill bit and below a closed blowout preventer mounted in a wellconduit at a subsurface location in the well, including the steps of:

controlling the fluid pressure in the well conduit above the closedblowout preventer to effect opening of the blowout preventer and forholding the blowout preventer open with controlled fluid pressure forcommunicating well conditions through the blowout preventer and theports of the drill bit; and

determining well conditions at a location below the open blowoutpreventer by flowing a sufficient quantity of well fluids through theblowout preventer and the well conduit to the surface.

9. The method as set forth in claim 8, wherein the step of controllingthe fluid pressure in the well conduit includes the steps of:

a. increasing the pressure in the well conduit above the blowoutpreventer to approach the value of the pressure in the well conduitbelow the blowout preventer;

b. opening the blowout preventer for equalizing the pressure in the wellconduit above the blowout preventer with the pressure in the wellconduit below the blowout preventer.

10. The method as set forth in claim 9, wherein the step of determiningwell conditions includes the steps of:

measuring the equalized pressure in the well conduit above the blowoutpreventer; and

compensating for the pressure head of well fluids to determine the wellpressure.

11. The method as set forth in claim 8, wherein the step of determiningwell conditions includes the step of: measuring the well conditions inthe well conduit above the blowout preventer.

12. The method as set forth in claim 1 1, including the step of:

compensating the measured well condition to determine the true wellcondition.

13. An inside blowout preventer well tool, including:

a frame adapted for mounting with a well conduit at a desired location;

closure means mounted with said frame for movement to and from an openposition enabling flow through the well conduit and a closed positionblocking flow through the well conduit; and

operator means operably connected with said closure means for movingsaid closure means to and from the open and closed positions, saidoperator means moving said closure means to the open position when thepressure in the well conduit exceeds a pressure level predeterminedbelow well fluid pressure externally of the well conduit and adjacentsaid frame.

14. The apparatus as set forth in claim 13, wherein said operator meansincludes:

piston means having a first pressure responsive surface for effectingmovement of said closure means to the open position in response topressure in the well conduit effecting urging on said first pressureresponsive surface.

15. The apparatus as set forth in claim 14, wherein said piston meansfurther includes:

a second pressure responsive surface for effecting movement of saidclosure means to the closed position in response to the pressureexteriorly of the well conduit and adjacent said frame.

16. The apparatus as set forth in claim 14, wherein:

said operator means is formed for predetermining the amount of pressureto which the pressure in the well conduit must vary from the pressureexteriorly of the well conduit for opening the closure means.

17. The apparatus as set forth in claim 14, including:

an expansible chamber formed by said frame and said operator means withsaid first pressure responsive surface exposed to the pressure in saidexpansible chamber; and

a pressure transmitting fluid disposed in said expansible chamberadjacent said first annular pressure responsive surface for transmittingthe pressure in the well conduit to said first pressure responsivesurface for effecting movement of said closure means while displacingthe well fluids from contact with said first pressure responsive surfaceto protect said first pressure responsive surface from the well fluidsin the well conduit.

18. An inside blowout preventer well tool, including:

a frame adapted for mounting with a well conduit at a desired location;

closure means mounted with said frame for movement to and from an openposition enabling flow through the well conduit and a closed positionblocking flow through the well conduit; and

operator means operably connected with said closure means for movingsaid closure means to and from the open and closed positions, saidoperator means moving said closure means to the open position when thepressure in the well conduit is substantially equal to the pressureexternally of the well conduit and adjacent said frame;

said operator means including:

piston means having a first pressure responsive surface for effectingmovement of said closure means to the open position in response topressure in the well conduit effecting urging on said first pressureresponsive surface;

an expansible chamber formed by said frame and said operator means withsaid first pressure responsive surface exposed to the pressure in saidexpansible chamber;

a pressure transmitting fluid in said expansible chamber fortransmitting the pressure in the well conduit to said first pressureresponsive surface for effect ing movement of said closure means whileprotecting said first pressure responsive surface from the well fluidsin the well conduit;

a movable sealing member enclosing said expansible chamber and havingfirst and second pressure responsive surfaces;

said first pressure responsive surface of said sealing member exposed topressure in the well conduit;

said second pressure responsive surface of said sealing member exposedto the pressure transmitting fluid in said expansible chamber, saidsealing member moving to transmit the pressure in the well conduiturging on said first surface to the pressure transmitting fluid in saidexpansible chamber by the urging of said second surface on said fluidpressure transmitting fluid wherein fluid pressure in the well conduitis transmitted into said expansible chamber.

19. The apparatus as set forth in claim 18, wherein:

said sealing member is a flexing diaphragm.

20. The apparatus as set forth in claim 19, wherein:

said diaphragm is in the form of a tube flexing radially to transmit thepressure into said expansible chamber.

21. The apparatus as set forth in claim 13, wherein:

said frame includes a tubular member adapted for connection with a wellconduit at upper and lower ends of said tubular member to form a portionof the well conduit.

22. The apparatus as set forth in claim 13, wherein:

said frame includes a tubular assembly dimensioned to be introduced inan enlarged portion of a flow passage of the well conduit at desiredlocation for controlling the flow through the flow passage, said tubularassembly operably secured at the enlarged portion of the flow passage ofthe well conduit after introduction by connection of an adjacent sectionof well conduit with the portion of the well conduit forming theenlarged portion of the flow passage.

23. The apparatus as set forth in claim 22, wherein:

said tubular assembly having an opening therethrough for enablingcommunication of the flow passage of the well conduit through saidtubular assembly, said opening having a cross-sectional flow areasubstantially equal to the cross-sectional flow area of the flow passageof the well conduit wherein a full opening well tool is provided.

24. The apparatus as set forth in claim 22, wherein:

a. said tubular assembly having an opening therethrough for enablingcommunication of the flow passage of the well conduit through saidtubular assembly; and

b. seal means carried by said tubular assembly for effecting a sealbetween said tubular assembly and the well conduit for directing theflow of fluid through the well conduit to flow through said openingthrough said tubular assembly.

25. The apparatus as set forth in claim 24, wherein:

said seal means carried by said tubular assembly for enabling fluidpressure introduced between said tubular assembly and the well conduitto withdraw said tubular assembly from the flow passage when the wellconduit is disconnected.

26. The apparatus as set forth in claim 13, wherein said closure means,includes:

27. The apparatus as set forth in claim 26, wherein: 6

said flow passage through said ball shaped member having across-sectional flow area substantially equal to the cross-sectionalflow area of the flow passage of the well conduit wherein a full openingwell tool is provided.

28. The apparatus as set forth in claim 13, wherein said operator meansincludes:

an operator member mounted with said frame for movement to and from afirst position for moving said closure means to the open position and asecond position for moving said closure means to the closed position.

29. The apparatus as set forth in claim 28, wherein:

said operator member forms a piston means having a first pressureresponsive surface for effecting movement of said operator member tomove said closure means to the open position in response to pressure inthe well conduit effecting urging on said first pressure responsivesurface.

30. The apparatus as set forth in claim 29, wherein said piston meansfurther includes:

a second pressure responsive surface for effecting movement of saidoperator member to move said closure means to the closed position inresponse to the pressure exteriorly of the well conduit adjacent saidframe.

31. The apparatus as set forth in claim 28, wherein:

a. said operator member includes a sleeve portion,

said sleeve portion having a first annular surface and a second annularsurface facing in opposite directions;

said first annular surface exposed to pressure in the well conduit forurging movement of said operator member to the first positionfor'opening said closure means in response to the pressure in the wellconduit urging on said first annular surface; and

c. said second annular surface exposed to pressure exteriorly of thewell conduit and adjacent said frame for urging movement of saidoperator member to the second position for closing said closure means inresponse to the pressure exteriorly of the well conduit and adjacentsaid frame urging on said second annular surface.

32. The apparatus as set forth in claim 31, wherein:

predetermining a difference in surface area between said first annularsurface and said second annular surface predetermines the amount ofpressure difference to move said operator member to operate said closuremeans.

33. The apparatus as set forth in claim 31, including:

means mounted with said frame for urging said operator to move to thefirst position for opening said closure means.

34. The apparatus as set forth in claim 31, including:

means mounted with said operator member for delaying movement of saidoperator from the first position to the second position to preventmomentary pressure fluctuations from closing said closure means.

35. The apparatus as set forth in claim 34, wherein said means fordelaying movement, includes:

a. said frame having a shoulder formed thereon:

b. a resilient deformable arm extending from said operator member;

c. a lug formed on said arm at a location spaced from said operatormember, said lug engaging said shoulder when said operator member is inthe first position to delay movement of said operator member to thesecond position.

36. The apparatus as set forth in claim 31, including:

an expansible chamber formed by said frame and said operator member withsaid first annular pressure responsive surface exposed to the pressurein said expansible chamber; and

b. a pressure transmitting fluid disposed in said expansible chamberadjacent said first annular pressure responsive surface for transmittingthe pressure in the well conduit to said first annular pressureresponsive surface for effecting movement of said closure means whiledisplacing the well fluids from contact with said first annular pressureresponsive surface to protect said first annular pressure responsivesurface from the well fluids in the well conduit.

An inside blowout preventer well tool, including:

a frame adapted for mounting with a well conduit at a desired location;

closure means mounted with said frame for movement to and from an openposition enabling flow through the well conduit and a closed positionblocking flow through the well conduit;

operator means operably connected with said closure means for movingsaid closure means to and from the open and closed positions, saidoperator means moving said closure means to the open position when thepressure in the well conduit is substantially equal to the pressureexternally of the well conduit and adjacent said frame;

said operator means including an operator member mounted with said framefor movement to and from a first position for moving said closure meansto the open position and a second position for moving said closure meansto the closed position;

said operator member includes a sleeve portion, said sleeve portionhaving a first annular surface and a second annular surface facing inopposite directions;

said first annular surface exposed to pressure in the well conduit forurging movement of said operator member to the first position foropening said closure means in response to the pressure in the wellconduit urging on said first annular surface;

said second annular surface exposed to pressure exteriorly of the wellconduit and adjacent said frame for urging movement of said operatormember to the second position for closing said closure means in responseto the pressure exteriorly of the well conduit and adjacent said frameurging on said second annular surface;

an expansible chamber formed by said frame and said operator member withsaid first annular pressure responsive surface exposed to the pressurein said expansible chamber;

a pressure transmitting fluid in said expansible chamber fortransmitting the pressure in the well conduit to said first annularpressure responsive surface for effecting movement of said closure meanswhile protecting said first pressure responsive surface from the wellfluids in the well conduit; and

a flexible diaphragm separating said expansible chamber from thepressure in the well conduit, said diaphragm flexing to transmit thepressure in the well conduit to said pressure transmitting fluid in saidexpansible chamber for urging on said first an nular pressure responsivesurface.

38. The apparatus as set forth in claim 37, wherein:

said diaphragm is in the form of a radially flexing sleeve transmittingthe pressure into said expansible chamber from the well conduit. 39. Amethod of operating a well tool having a pressure comparer forcontrolling undesired flow in a well conduit, including the steps of:

mounting the well tool with the well conduit to control flow through thewell conduit;

sensing the fluid pressure exteriorly of the well conduit adjacent thewell tool;

transmitting with a transmitting fluid the well fluid pressed in thewell conduit to a location in the well tool for comparing while holdingthe well fluid pressure from contact with a comparer; comparing thesensed pressure exteriorly of the well conduit with the fluid pressurein the well conduit transmitted by the transmitting fluid; and closingthe well too] to block flow through the well conduit when the sensedpressure exceeds the pressure in the well conduit by a predeterminedamount.

40. A method of operating a well tool having a pressure comparer forcontrolling undesired flow in a well conduit, including the steps of:

mounting the well tool with the well conduit to control flow through thewell conduit;

sensing the fluid pressure exteriorly of the well conduit adjacent thewell tool;

transmitting with a transmitting fluid the fluid pressure in the wellconduit to a location in the well tool for comparing while blockingcontact of the well fluids with the comparer;

comparing the sensed pressure exteriorly of the well conduit with thefluid pressure in the well conduit; and

opening the well tool to enable flow through the well conduit when thepressure in the well conduit is substantially equal to the sensedpressure.

41. The method as set forth in claim 40, including the step of:

locating the well tool in the flow passage of the well conduit to enabledesired changing of the well tool by disconnecting the well conduit atone location.

42. The method as set forth in claim 39, wherein the step of mountingincludes the step of:

arranging the well tool to provide a substantially full opening flowpassage through the well conduit when the well tool is opened.

43. The method as set forth in claim 40, wherein the step of mountingincludes the step of:

arranging the well tool to provide a substantially full opening flowpassage through the well conduit when the well tool is opened.

44. The method as set forth in claim 39, including the steps of:

controlling the pressure in the well conduit to open the well tool; and

determining the value of the sensed pressure through the open well tool.

45. The method as set forth in claim 40, including the steps of:

controlling the pressure in the well conduit to open the well tool; and

determining the value of the sensed pressure through the open well tool.

i I t

1. A method of operating a well tool for controlling undesired flow in awell conduit, including the steps of: mounting the well tool with thewell conduit to control flow through the well conduit; sensing the fluidpressure exteriorly of the well conduit adjacent the well tool;comparing the sensed pressure exteriorly of the well conduit with thhefluid pressure in the well conduit; and opening the well tool to enableflow in either direction through the well conduit when the pressure inthe well conduit approaches within a predetermined amount of the sensedpressure exteriorly of the well conduit wherein the well tool is openedto enable the flow when the pressure in the well conduit is less thanthe pressure exteriorly of the well tool by the predetermined amount. 2.The method as set forth in claim 1, including the step of: closing thewell tool to block flow through the well conduit when the sensedpressure exceeds the pressure in the well conduit by the predeterminedamount of pressure.
 3. The method as set forth in claim 1, including thestep of: latching the well tool open to delay operation sufficiently toprevent momentary pressure fluctuations from operating the well tool. 4.The method as set forth in claim 3, including the step of: releasing thelatch when the sensed pressure exceeds the pressure in the well conduitby the predetermined amount of pressure for closing the well tool. 5.The method as set forth in claim 1, wherein the step of mountingincludes the step of: locating the well tool in the flow passage of thewell conduit to enable desired changing of the well tool bydisconnecting the well conduit at one location.
 6. The method as setforth in claim 1, wherein the step of mounting includes the step of:arranging the well tool to provide a substantially full opening flowpassage through the well conduit when the well tool is opened.
 7. Themethod as set forth in claim 1, including the steps of: a. controllingthe pressure in the well conduit to open the well tool; and b.determining the value of the sensed pressure through the open well tool.8. A method of determining well conditions at a location adjacent aported drill bit and below a closed blowout preventer mounted in a wellconduit at a subsurface location in the well, including the steps of:controlling the fluid pressure in the well conduit above the closedblowout preventer to effect opening of the blowout preventer and forholding the blowout preventer open with controlled fluid pressure forcommunicating well conditions through the blowout preventer and theports of the drill bit; and determining well conditions at a locationbelow the open blowout preventer by flowing a sufficient quantity ofwell fluids through the blowout preventer and the well conduit to thesurface.
 9. The method as set forth in claim 8, wherein the step ofcontrolling the fluid pressure in the well conduit includes the stepsof: a. increasing the pressure in the well conduit above the blowoutpreventer to approach the value of the pressure in the well conduitbelow the blowout preventer; b. opening the blowout preventer forequalizing the pressure in the well conduit above the blowout preventerwith the pressure in the well conduit below the blowout preventer. 10.The method as set forth in claim 9, wherein the step of determining wellconditions includes the steps of: measuring the equalized pressure inthe well conduit above the blowout preventer; and compensating for thepressure head of well fluids to determine the well pressure.
 11. Themethod as set forth in claim 8, wherein the step of determining wellconditions includes the step of: measuring the well conditions in thewell conduit above the blowout preventer.
 12. The method as set forth inclaim 11, including the step of: compensating the measured wellcondition to determine the true well condition.
 13. An inside blowoutpreventer well tool, including: a frame adapted for mounting with a wellconduit at a desired location; closure means mounted with said frame formovement to and from an open position enabling flow through the wellconduit and a closed position blocking flow through the well conduit;and operator means operably connected with said closure means for movingsaid closure means to and from the open and closed positions, saidoperator means moving said closure means to the open position when thepressure in the well conduit exceeds a pressure level predeterminedbelow well fluid pressure externally of the well conduit and adjacentsaid frame.
 14. The apparatus as set forth in claim 13, wherein saidoperator means includes: piston means having a first pressure responsivesurface for effecting movement of said closure means to the openposition in response to pressure in the well conduit effecting urging onsaid first pressure responsive surface.
 15. The apparatus as set forthin claim 14, wherein said piston means further includes: a secondpressure responsive surface for effecting movement of said closure meansto the closed position in response to the pressure exteriorly of thewell conduit and adjacent said frame.
 16. The apparatus as set forth inclaim 14, wherein: said operator means is formed for predetermining theamount of pressure to which the pressure in the well conduit must varyfrom the pressure exteriorly of the well conduit for opening the closuremeans.
 17. The apparatus as set forth in claim 14, including: anexpansible chamber formed by said frame and said operator means withsaid first pressure responsive surface exposed to the pressure in saidexpansible chamber; and a pressure transmitting fluid disposed in saidexpansible chamber adjacent said first annular pressure responsivesurface for transmitting the pressure in the well conduit to said firstpressure responsive surface for effecting movement of said closure meanswhile displacing the well fluids from contact with said first pressureresponsive surface to protect said first pressure responsive surfacefrom the well fluids in the well conduit.
 18. An inside blowoutpreventer well tool, including: a frame adapted for mounting with a wellconduit at a desired location; closure means mounted with said frame formovement to and from an open position enabling flow through the wellconduit and a closed position blocking flow through the well conduit;and operator means operably connected with said closure means for movingsaid closure means to and from the open and closed positions, saidoperator means moving said closure means to the open position When thepressure in the well conduit is substantially equal to the pressureexternally of the well conduit and adjacent said frame; said operatormeans including: piston means having a first pressure responsive surfacefor effecting movement of said closure means to the open position inresponse to pressure in the well conduit effecting urging on said firstpressure responsive surface; an expansible chamber formed by said frameand said operator means with said first pressure responsive surfaceexposed to the pressure in said expansible chamber; a pressuretransmitting fluid in said expansible chamber for transmitting thepressure in the well conduit to said first pressure responsive surfacefor effecting movement of said closure means while protecting said firstpressure responsive surface from the well fluids in the well conduit; amovable sealing member enclosing said expansible chamber and havingfirst and second pressure responsive surfaces; said first pressureresponsive surface of said sealing member exposed to pressure in thewell conduit; said second pressure responsive surface of said sealingmember exposed to the pressure transmitting fluid in said expansiblechamber, said sealing member moving to transmit the pressure in the wellconduit urging on said first surface to the pressure transmitting fluidin said expansible chamber by the urging of said second surface on saidfluid pressure transmitting fluid wherein fluid pressure in the wellconduit is transmitted into said expansible chamber.
 19. The apparatusas set forth in claim 18, wherein: said sealing member is a flexingdiaphragm.
 20. The apparatus as set forth in claim 19, wherein: saiddiaphragm is in the form of a tube flexing radially to transmit thepressure into said expansible chamber.
 21. The apparatus as set forth inclaim 13, wherein: said frame includes a tubular member adapted forconnection with a well conduit at upper and lower ends of said tubularmember to form a portion of the well conduit.
 22. The apparatus as setforth in claim 13, wherein: said frame includes a tubular assemblydimensioned to be introduced in an enlarged portion of a flow passage ofthe well conduit at desired location for controlling the flow throughthe flow passage, said tubular assembly operably secured at the enlargedportion of the flow passage of the well conduit after introduction byconnection of an adjacent section of well conduit with the portion ofthe well conduit forming the enlarged portion of the flow passage. 23.The apparatus as set forth in claim 22, wherein: said tubular assemblyhaving an opening therethrough for enabling communication of the flowpassage of the well conduit through said tubular assembly, said openinghaving a cross-sectional flow area substantially equal to thecross-sectional flow area of the flow passage of the well conduitwherein a full opening well tool is provided.
 24. The apparatus as setforth in claim 22, wherein: a. said tubular assembly having an openingtherethrough for enabling communication of the flow passage of the wellconduit through said tubular assembly; and b. seal means carried by saidtubular assembly for effecting a seal between said tubular assembly andthe well conduit for directing the flow of fluid through the wellconduit to flow through said opening through said tubular assembly. 25.The apparatus as set forth in claim 24, wherein: said seal means carriedby said tubular assembly for enabling fluid pressure introduced betweensaid tubular assembly and the well conduit to withdraw said tubularassembly from the flow passage when the well conduit is disconnected.26. The apparatus as set forth in claim 13, wherein said closure means,includes: a substantially ball-shaped member having a flow passageformed therethrough, said ball shaped member rotating to and from theopen and closed positions for positioning said flow passage forcontrolling flow through the Well conduit.
 27. The apparatus as setforth in claim 26, wherein: said flow passage through said ball shapedmember having a cross-sectional flow area substantially equal to thecross-sectional flow area of the flow passage of the well conduitwherein a full opening well tool is provided.
 28. The apparatus as setforth in claim 13, wherein said operator means includes: an operatormember mounted with said frame for movement to and from a first positionfor moving said closure means to the open position and a second positionfor moving said closure means to the closed position.
 29. The apparatusas set forth in claim 28, wherein: said operator member forms a pistonmeans having a first pressure responsive surface for effecting movementof said operator member to move said closure means to the open positionin response to pressure in the well conduit effecting urging on saidfirst pressure responsive surface.
 30. The apparatus as set forth inclaim 29, wherein said piston means further includes: a second pressureresponsive surface for effecting movement of said operator member tomove said closure means to the closed position in response to thepressure exteriorly of the well conduit adjacent said frame.
 31. Theapparatus as set forth in claim 28, wherein: a. said operator memberincludes a sleeve portion, said sleeve portion having a first annularsurface and a second annular surface facing in opposite directions; b.said first annular surface exposed to pressure in the well conduit forurging movement of said operator member to the first position foropening said closure means in response to the pressure in the wellconduit urging on said first annular surface; and c. said second annularsurface exposed to pressure exteriorly of the well conduit and adjacentsaid frame for urging movement of said operator member to the secondposition for closing said closure means in response to the pressureexteriorly of the well conduit and adjacent said frame urging on saidsecond annular surface.
 32. The apparatus as set forth in claim 31,wherein: predetermining a difference in surface area between said firstannular surface and said second annular surface predetermines the amountof pressure difference to move said operator member to operate saidclosure means.
 33. The apparatus as set forth in claim 31, including:means mounted with said frame for urging said operator to move to thefirst position for opening said closure means.
 34. The apparatus as setforth in claim 31, including: means mounted with said operator memberfor delaying movement of said operator from the first position to thesecond position to prevent momentary pressure fluctuations from closingsaid closure means.
 35. The apparatus as set forth in claim 34, whereinsaid means for delaying movement, includes: a. said frame having ashoulder formed thereon: b. a resilient deformable arm extending fromsaid operator member; c. a lug formed on said arm at a location spacedfrom said operator member, said lug engaging said shoulder when saidoperator member is in the first position to delay movement of saidoperator member to the second position.
 36. The apparatus as set forthin claim 31, including: an expansible chamber formed by said frame andsaid operator member with said first annular pressure responsive surfaceexposed to the pressure in said expansible chamber; and b. a pressuretransmitting fluid disposed in said expansible chamber adjacent saidfirst annular pressure responsive surface for transmitting the pressurein the well conduit to said first annular pressure responsive surfacefor effecting movement of said closure means while displacing the wellfluids from contact with said first annular pressure responsive surfaceto protect said first annular pressure responsive surface from the wellfluids in the well conduit.
 37. An inside blowout preventer well tool,including: a frame adapted for mountiNg with a well conduit at a desiredlocation; closure means mounted with said frame for movement to and froman open position enabling flow through the well conduit and a closedposition blocking flow through the well conduit; operator means operablyconnected with said closure means for moving said closure means to andfrom the open and closed positions, said operator means moving saidclosure means to the open position when the pressure in the well conduitis substantially equal to the pressure externally of the well conduitand adjacent said frame; said operator means including an operatormember mounted with said frame for movement to and from a first positionfor moving said closure means to the open position and a second positionfor moving said closure means to the closed position; said operatormember includes a sleeve portion, said sleeve portion having a firstannular surface and a second annular surface facing in oppositedirections; said first annular surface exposed to pressure in the wellconduit for urging movement of said operator member to the firstposition for opening said closure means in response to the pressure inthe well conduit urging on said first annular surface; said secondannular surface exposed to pressure exteriorly of the well conduit andadjacent said frame for urging movement of said operator member to thesecond position for closing said closure means in response to thepressure exteriorly of the well conduit and adjacent said frame urgingon said second annular surface; an expansible chamber formed by saidframe and said operator member with said first annular pressureresponsive surface exposed to the pressure in said expansible chamber; apressure transmitting fluid in said expansible chamber for transmittingthe pressure in the well conduit to said first annular pressureresponsive surface for effecting movement of said closure means whileprotecting said first pressure responsive surface from the well fluidsin the well conduit; and a flexible diaphragm separating said expansiblechamber from the pressure in the well conduit, said diaphragm flexing totransmit the pressure in the well conduit to said pressure transmittingfluid in said expansible chamber for urging on said first annularpressure responsive surface.
 38. The apparatus as set forth in claim 37,wherein: said diaphragm is in the form of a radially flexing sleevetransmitting the pressure into said expansible chamber from the wellconduit.
 39. A method of operating a well tool having a pressurecomparer for controlling undesired flow in a well conduit, including thesteps of: mounting the well tool with the well conduit to control flowthrough the well conduit; sensing the fluid pressure exteriorly of thewell conduit adjacent the well tool; transmitting with a transmittingfluid the well fluid pressed in the well conduit to a location in thewell tool for comparing while holding the well fluid pressure fromcontact with a comparer; comparing the sensed pressure exteriorly of thewell conduit with the fluid pressure in the well conduit transmitted bythe transmitting fluid; and closing the well tool to block flow throughthe well conduit when the sensed pressure exceeds the pressure in thewell conduit by a predetermined amount.
 40. A method of operating a welltool having a pressure comparer for controlling undesired flow in a wellconduit, including the steps of: mounting the well tool with the wellconduit to control flow through the well conduit; sensing the fluidpressure exteriorly of the well conduit adjacent the well tool;transmitting with a transmitting fluid the fluid pressure in the wellconduit to a location in the well tool for comparing while blockingcontact of the well fluids with the comparer; comparing the sensedpressure exteriorly of the well conduit with the fluid pressure in thewell conduit; and opening the well tool to enable flow through thE wellconduit when the pressure in the well conduit is substantially equal tothe sensed pressure.
 41. The method as set forth in claim 40, includingthe step of: locating the well tool in the flow passage of the wellconduit to enable desired changing of the well tool by disconnecting thewell conduit at one location.
 42. The method as set forth in claim 39,wherein the step of mounting includes the step of: arranging the welltool to provide a substantially full opening flow passage through thewell conduit when the well tool is opened.
 43. The method as set forthin claim 40, wherein the step of mounting includes the step of:arranging the well tool to provide a substantially full opening flowpassage through the well conduit when the well tool is opened.
 44. Themethod as set forth in claim 39, including the steps of: controlling thepressure in the well conduit to open the well tool; and determining thevalue of the sensed pressure through the open well tool.
 45. The methodas set forth in claim 40, including the steps of: controlling thepressure in the well conduit to open the well tool; and determining thevalue of the sensed pressure through the open well tool.